- "Rule number one. We're not just here to make a cure, we're here to make a choice."
- —Cisco Ramon to Caitlin Snow[src]
The meta-human cure, also commonly referred to as the cure or the meta cure, is a cure created by Cisco Ramon and Caitlin Snow. The cure is used to remove a meta-human's powers by suppressing the dark matter in their pituitary gland. While Team Flash has plenty of the cure on hand, they swore to never use it as a weapon, and only administer it to those who give consent.
After Cisco's hands got cut by Cicada's dagger (which was capable of negating the powers of meta-humans who gained their abilities from exposure to dark matter), Cisco began having trouble using his powers. After removing small shards from the wounds in his hands inflicted Cicada's dagger, Cisco decided to run some tests on the shards and his hands' tissue. These tests revealed that the shards hadn't been dampening Cisco's powers but removing them, inspiring Cisco to use this information to make a meta-human cure.
At first Caitlin Snow wasn't on board with the idea as she thought it wasn't necessary for a cure to exist; neither was Killer Frost, who sabotaged Cisco's first attempt at making the cure. When she did that, Cisco told her that she ruined his only chance to have a normal life. This speech caused Caitlin to understand Cisco. That's why she took him to her dad's old lab to use his research to do the opposite of creating a meta-gene. In exchange for them working on it together they set up some rules, the most important one being that they will never force the cure on anyone.
Killer Frost still didn't agree with the creation of the cure so she tried to sabotage it by making changes in Caitlin's equations, while Cisco was work in in the Tannhauser offsite. Caitlin later realized she needed a DNA sample from a meta-human who hasn't fully bonded with dark matter to make the cure. To get her point of view through to Caitlin, Killer Frost destroyed all of her equations before getting recruited to help Team Flash locate meta's that were in danger. After getting a speech from Ralph Dibny why she shouldn't be afraid of Caitlin making the cure and possibly take it, she decided to help them so she took some of Cicada's blood when fighting him and gave it to Caitlin.
Cisco kept working on the cure, seeing that something was missing. After being taken to a bar by Ralph, he starts talking with Kamilla Hwang. After she told him she had a sister, he realized that that was what he needed, DNA samples from siblings who were both exposed to dark matter, where one of them became a meta-human and the other one didn't. He then located a pair of siblings that fit this description for their research, and informed the team that the cure was as good as done. Barry then revealed he wanted to use the cure on Cicada.
Cisco sent the sample of the cure to Caitlin to test if it could work. Her test showed that everything should check out. She then sent it back to Cisco for final processing. She then revealed that giving the cure to Cicada wouldn't be that easy, since the cure isn't instant and takes about a minute to work and they have to keep him still during that time. Caitlin had a solution for this. They needed a Neuro-Stasis Field Generator, which was located in Goldface's black market. Barry and Ralph tried to get their hands on the Generator, but failed. Luckily for them, Iris West found out about Cicada's wound in his chest. Knowing about his weakness gives them an other way to give him the cure.
Cisco finished the cure but then found out that they had to wait twenty-nine days before they could use the cure. It had to synthesize for that long, unless they took it into the Speed Force. So, Barry took the cure with him into the Speed Force where it would take about one hour for the compound to synthesize by using the tachyons located in the Speed Force. When Barry returned, the cure was fully synthesized and ready to use.
Now that the cure was ready, they needed to test it on a meta-human. After talking about multiple options, Team Flash decided that the best meta to try the cure on is King Shark who was being held at A.R.G.U.S. But, due to an interference from Grodd, King Shark escaped. When they found him again The Flash just used the cure on him without asking. King Shark then returned to his human form, Shay Lamden. Back at S.T.A.R. Labs, Cisco and Caitlin were upset with Barry because he used the cure on him without asking. There was still a problem. Since the cure was developed to bring out meta's human parts, Shay's animal parts fought back, causing in some dark matter that stayed in his pituitary gland, which meant he wasn't going to be human forever. Caitlin made sure they could ajust the cure so that it could work on him. He later gave up the chance to be fully cured to save Central City from Grodd by changing back into King Shark. After all this happened Barry apologized about using the cure on him and then came up with the idea to offer the cure to Cicada.
After discussing how they could offer the cure to Cicada without having to fight him, they located him. Killer Frost made sure his dagger wouldn't be able to work so that The Flash could talk to Cicada. After The Flash gave Cicada a speech about choosing the cure for his legacy, Cicada went on to fight him, stating that he doesn't care about his legacy. When confronted again, The Flash shared the news that his niece, Grace Gibbons, was also a meta-human. So, they came to the agreement to first cure Orlin and then Grace. Orlin was taken to S.T.A.R. Labs to be given the cure. After he was cured, they patched up the wound in his chest.
Prototypes of the cure were later taken by future Grace to try to use them with the Cryo-Atomizer to spread the cure all over Central City. Since these prototypes aren't the finished product, they have a deadly consequence when taken without proper treatment.
Grace then threatened to use this weapon, which is why Team Flash decided to distribute the cure, to meta-humans who wanted to be safe, at CCPD. They cured an unknown number of metas, but some people, like Renee Adler, decided to keep their powers after all. Later, they didn't have to distribute the cure anymore since Team Flash stopped Grace's weapon, and managed to cure Grace's present-day self, erasing her serial killer future self from existence.
Known meta-humans cured by it
Formerly cured meta-humans
- Shay Lamden/King Shark (needed a stronger cure; lost the chance to be cured again after turning back into King Shark)
- Given the fact the cure works by removing the dark matter from the subject's system, it won't have any effect on meta-humans that were created otherwise, such as Killer Frost.
- In spite of this, Killer Frost sabotaged Caitlin's efforts to work on the cure multiple times, due to the fact that she was afraid that Caitlin may someday decide to take the cure, and Killer Frost would vanish as a result, leaving Caitlin with no one to protect her.